Second, to perform multiple posts, It is simple, create multiple action methods and decorate with the [HttpPost] attrib. Use the [ActionName("MyAction")] to assign custom names, etc. Will come to jQuery in the fourth point below

Third, First of all, posting multiple SIMPLE types in a single action is not possible.
Moreover, there is a special format to post even a single simple type (apart from passing the parameter in the query string or REST style).
This was the point that had me banging my head with Rest Clients (like Fiddler and Chrome's Advanced REST client extension) and hunting around the web for almost 5 hours when eventually, the following URL proved to be of help. Will quote the relevant content for the link might turn dead!

Content-Type: application/x-www-form-urlencoded
in the request header and add a = before the JSON statement:
={"Name":"Turbo Tina","Email":"na@Turbo.Tina"}